<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <style type="text/css">
			.fater {
				width: 600px;
				height: 300px;
				background-color: pink;
				position: relative;
			}
			.son {
				width: 200px;
				height: 100px;
				background-color: skyblue;
				position: absolute;
				left: 0;
		
				top: 50%;
				margin-top: -50px;
				
			}
        </style>
    </head>
    <body>
    <div class="fater">
    	<div class="son"></div>
    </div>
    </body>
</html>